Dar Es Salaam, Aug 10 : At least 20 people were killed and 15 others injured after three vehicles and a tractor were involved in multiple collisions in Tanzania's northern district of Kahama in Shinyanga region, police said. The Shinyanga regional police commander Leonard Nyandahu said on Tuesday that in one of the accidents, three people travelling in a salon car died on the spot after their car rammed into a stationary tractor on Monday evening. Nyandahu told a news conference that another 17 people travelling in a mini-bus died on the spot after their bus collided with a truck on Monday evening when the driver of the bus tried to avoid the stationary tractor, Xinhua news agency reported. He added that the accidents occurred at 10 p.m., adding that three of the injured people were in critical condition. President Samia Suluhu Hassan, who is inspecting the Njombe region in the country's south, sent a condolence message to the Shinyanga regional commissioner Sophia Mjema following the accidents. "I am joining the families in mourning the loss of their beloved relatives and friends," said President Hassan in a statement issued by the Directorate of Presidential Communications, wishing the injured persons quick recovery. /IANS